Aircraft supercharging arrangement



Dec. 25, 1945. c w, sMlTH 2,391,486

AIRCRAFT SUPERCHARGING ARRANGEMENT Filed 061... 26, l939 Ifiventor:

Chester \A/- Smith,-

is Atborn y.

Patented Dec. 25, 1945 Chester W. smith, asslgnor to General Electric Company, a corporation of New York Application October 28, 1889, Serial No. 801,418 2 (CL 98-15) This invention relates to aircraft supercharging arrangements including multi-stage superchargers for supplying air under pressure to a combustion engine, a sealed cabin, or like consumer. The supercharging of combustion err-'- gines renders the operation of such engines eillcient at varying altitudes and the supercharging of sealed cabins for the pilot and the passengers at high altitudes eliminates the ill eflect on passengers due to low atmospheric pressure. In the case of multi-stage supercharging arrangements it has been customary heretofore to connect these stages in series at high altitudes and to disconnect on of the stages or render it inoperative at low altitudes. In arrangements of this kind difllculty is experienced at low altitudes if the supercharger stage or stages for operation at such low altitudes fail.

The object of my invention is to provide an improved supercharger arrangement whereby aircraft maybe effectivelysuperchargedatlowaltitude upon failure of one of the supercharger stages. This is accomplished in accordance with my invention by the provision of a multi-stage supercharging arrangement including at least two stages'and means for connecting the stages in parallel at low altitudes and. connecting them in series at high altitudes. The change from parallel to series operation and vice-versa is preferably accomplished automatically by a device responsive to variations in altitude or like operating condition.

For a better understanding of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto inconnection with the accompanying drawing.

The single figure of the drawing illustrates an aircraft supercharger arrangement embodying my invention.

The arrangement comprises an aircraft with a pilot cabin Ill and a passenger cabin I I. The aircraft is operated by a combustion engine l2 driving a propeller iii. A consumer, in the present instance the passenger cabin I I, is supercharged by a supercharging arrangement which in the present example includes two compressors or compressor stages it and 15, each having an impeller driven from the crank shaft of the combustion engine i2. Means are provided for alternately connecting the two compressors or compressor stages H, 15 in parallel and in series. To this end the first compressor or compressor stage ll has an inlet conduit It for receiving air to be compressed and a discharge conduit II with branches. l8 and it including valves 28 and 2! respectively for connecting the first compressor or compressor stage I either to the inlet of the second compressor or compressor stage II or to the cabin II. The second compressor or compressor stage 15 has an inlet which may be connected to the outlet of the first compressor by the aforementioned branch conduit II or directly to the atmosphere by a conduit 22 with a valve 28. Theoutlet of the second compressor-ll is connected by a conduit 2| to the cabin II.

The valves 20, 2| and 28 are shown in a position in which the two compressors are connected in parallel, the valve 28 being closed and the valves Hand 23 open. Under this condition the compressors I4 and I5 receive air directly from.

the atmosphere through the inlet conduits l8 and 22 respectively and they discharge compressed air to the cabin ll through the'discharge conduits l8 and 24. Upon reversing of the valves, that is, opening of valve 28 and closing of valves 2i and 23, the compressors are connected in series. Un-, der this condition the air compressed by the first compressor M is discharged through the branch conduit l8 into the inlet of the second compressor It to be furthercompressed in the latter and discharged therefrom through the conduit 24 to the cabin ll.

The operation of the valves is preferably effected automatically. To this end each valve is provided with an arm 25 connected to an electric which includes a source of energy 80 and a con-' Closing of the contacttact-making device 3|. making device causes energization of the operating coils 28 whereby the positions of the valves are reversed against the biasing forces of the springs 28. The contact-making device ii is operated automatically by a device responsive to variations of an operating condition, in the present example a device 32 located'in the cabin II and responsive to pressure changes therein. The device 32 comprises an evacuated bellows 88 and a spring 84 preventing the bellows mm collapsing. The upper end of the device 28 is filed and the lower end of the bellows 82 is connected H decreases, thereby causing the bellows 33.

expand and as the pressure in the cabin reaches a certain low value the device 32 effects closing of the contact-making device 3|. This closes the electric circuit for the relays 26 and, as pointed out above, reverses the positions of the valves to change the connection of the compressors i4 and 55 from parallel to series connection.

What I claim as new and desire'to secure by Letters Patent of the United States is:

1. In an aircraft, the combination of means forming a compartment requiring air under pressure during fli ht oi the aircraft and from which compartment said air is consumed during operation of the aircraft, compressor means having first and second stages, conduit means for connecting said compressor means to said compartment to supply compressed air thereto, said last named means including valves arranged to connect the compressor stages in parallel in one position of the valves and in series in another position of the valves, and means for operating said valves including a relay for each valve, an 80 electric circuit for the relays including a contact During operation the compressors l4 making and breaking memberand a pressure responsive device subject to pressure changes in the compartment and connected to said contact making and breaking member for automatically reversing the valve positions upon the compartment pressure dropping'to a predetermined low value to connect the stagesin series.

2.- In an aircraft, the combination of means forming a compartment requiring air under pressure during flight of the aircraft and from which compartment said air is consumed during operation of the aircraft, an engine, two compressors driven from the engine, conduit means for connecting the compressors to the compartment to supply compressed air thereto, said conduit means including valves arranged to connect the compressors in parallel in one position of the valves during operation at low altitude and in series in another position of the valves during operation at high altitude, and means for operating said valves including a device responsive to the air pressure in the compartment for automatically positioning the valves to connect the compressors in parallel in response to a predetermined high value of the compartment pressure and for automatically reversing the valve position to connectthe compressors in series in response to a predetermined low value of the compartment pressure.

' CHESTER W. SMITH. 

